REPOKT ON THE BOTANY OF THE ATLANTIC ISLANDS. 59 



they belong to types of the widest dispersion, which may have been introduced through 

 the agency of man, direct or indirect ; whilst others are maritime plants which owe their 

 presence to the action of the sea. In treating of the origin of the flora of St Helena, we 

 should, therefore, exclude this modern element and confine ourselves to the facts relating 

 to the ancient element. Sir Joseph Hooker, 1 with practically the same facts before 

 him (for the small accession of species in the present work could in no way modify 

 them), was of opinion that, on the whole, the affinities of the flora were with the South 

 African. "From such fragmentary data," he says, <: it is difficult to form any exact 

 conclusions as to the affinities of this flora, but I think it may safely be regarded as an 

 African one, and characteristic of Southern extra-tropical Africa. The genera Phylica, 

 Pelargonium, Mesembryanthemum, Osteospcrmum [Tripteris] and Walilenbergia are 

 eminently characteristic of Southern extra-tropical Africa, and I find amongst the others 

 scarce any indication of an American parentage, except a plant referred to Physalis" 

 [Mellissia], 



In arriving at this conclusion Sir Joseph Hooker does not appear to have specially 

 considered the arboreous Composite, some of which find equal or closer affinities among 

 American types. They number nine species, and are here referred to five genera. At 

 a later date, Mr Bentham, in his admirable essay on the Composite, 2 set forth his views 

 of the relationships of the St Helena forms in the following words : " The expiring flora of 

 the isle of St Helena is as remarkable in Composite as in other orders, in its distant con- 

 nections. Although nearer to Africa than to any other continent, those denizen Composite 

 which bear evidence of the greatest antiquity have their affinities for the most part in 

 South America, whilst the colonists of a more recent character are South African. Seven 

 endemic species 3 are known — Commidendron, four species, and Melanodendron , Petrohium. 

 and Psiadia, one species each. 4 All, except one species of Commidendron, have more or 

 less of the insidar arborescent character. Commidendron and Melanodendron are among 

 the woody Asteroid forms exemplified in the Antarctic-American Chiliotrichium, in the 

 Andine Diplostcphinm, and in the Australasian Olearia. Petrohium is one of three genera, 

 remains of a group probably of great antiquity, of which the two others are Podanthus in 

 Chili and Astemma in the Andes. The Psiadia is an endemic species of a genus otherwise 

 Mascarene, or of Eastern Africa, presenting a geographical connection analogous to the St 

 Helena Melhanice with the Mascarene Trochetia." 



From the foregoing it would seem that the ancient element in the indigenous 

 vegetation is the remnant of a flora that was formerly spread over a wide area, and is 

 now only represented in isolated distant spots ; and that certain types of this flora, the 



1 Lecture on Ins-alar Floras, reprint, p. 7. 



2 Notes on the History, Classification, and Geographical Distribution of the Compositae, Journ. Linn. Soc. 

 Lond., (Botany) vol. xiii. p. 563. 



3 Including the annual Tripteris burchellii, there are ten endemic species. 



4 The two very remarkable species of Senecio are not taken into account. 



